Multioffice telephone system



Sept. 16, 1930. R. F. STEHLIK IULHOFFICE TELEPHONE SYSTEI Original Filed March 14. 1927 4 Sheets-Sheet 1 Sept. 16, 1930. R. F. STEHLIK IULTIOFFICE TELEPHONE SYSTEI.

Original Filed larch 14. 1927 Sept. 16, 1930. R. F. STEHLIK 1,775,834

uumxonzc: 'mnnrnoma srsm Original Filed larch 14. 1927 4 Sheets-Sheet s SUP InTT-Tu? ELZdUZFZ'LF ETEhlik Patented Sept. 16, 1930 Pl a'i iilit 'i GFFICE RUDOLPH FRANK STE-ERIK, 01" CHICAGO, ILLIIIOIS, ASSIGNOR 'lO RESERVE HOLDING COMPANY, OF CHZGAGO, ILLINOIS, A CORPORATION OF DELAWARE MULTIZOFFICE TELEPHON SYSTEM Application filed March 14;, 1927, Seria1 No. 175,187. Renewed January 251930.

This invention relates in general to multioiilce telephone systems but more particularly to such systems as comprise in one network oiiices or exchanges of two different kinds, the oifices of one kind being manual oliices wherein' connections are completed by operators, while the other kind of otfices are automatic offices whose connections are completed by means of automatic switches, and the object oi": the invention is to provide new and improved circuit arrangements for handling interoliice callsbetween the automatic and manual exchanges. V

Systems having both kinds of exchanges as above pointed out are becoming quite common and may arise either by consolidation of existing manual and automatic systems, serving the same territory, or by the process 01": changing over a manual system to an automatic system. Usually in the latter case only one oilice at a time is converted from manual to automatic and it follows that during the period of transition there will necessarily be both kinds of oilices in operation. However the above situation may arrive, it is necessary to provide suitable circuitarrangements for handling calls from the manual to the automatic oflices, and from the automatic oi'fices to the manual oiiices. The present invention is concerned only with the latter class of calls, and provides certain improvements in systems comprising automatic to manual trunks which. are accessible to selector switches in the automatic ofi'ices and terminate in plugs in front or" a B operator at the manual office, together with call registers for registering the digits telephone numbers called by automatic subscribers when the trunks are taken for use, and an indicating device upon which such numbers shown to the operator one after the other as fast as she can complete the desired connections.

The present invention may be considered to be an improvement on the system disclosed in Patent No. 1,539,925, issued June 2, 1925. The main feature of the invention may be said to consist in the provision of improved plug ended cord circuits for completing calls from automatic exchanges to 7 subscribers whose lines terminate in a manual call indilll cator olfice. One of the features of the improved cord circuit consists in the provisions for giving the automatic subscriber a busy tone from the cord circuit.

Another feature consists in the provision for busying at the automatic exchange, the two conductor outgoing trunks extending to the manual call indicator exchange under various operating conditions which are encountered.

A still further feature consists in the pro- Vision 01"- an improved'pre-selecting rotary line switch for preselecting idle register sets, together with the special method of multiplying the various register sets at an intermediate distributing frame.

, A still further feature of the invention consists in the provision for completing a call which may come into an operators position after the last of the normally used register sets is taken into use and before all the trunks leading to the operators position have been made busy.

Other features consist in the provision for positively guarding an idle register set against seizure in case it does not properly release; in the provision of an improved time switch which releases each time a digit is dialled; in the provision of circuit arrangements whereby the same circuit which cuts off the ringing current also transmits ringing induction; and in the provision of various other detailed improvements, all of which will be pointed out and described fully in the detailed description which follows:

In the drawings, comprising Figs. 1, 2, 3, and 4, there is shown by means of the usual circuit diagrams the apparatus and circuit connections thereof which is involved in a complete connection extending from-the automatic substation A, Fig. 1, to a manual'substation A, Fig. 2.

The apparatus indicated in Fig. 1, is located in an automatic exchange, while the apparatus indicated inFigs. 2, 3, and 4, is located in a manual exchange. Inasmuch as the automatic switching equipment itself and the manual equipment are both well known and of the usual type, no detailed description of the mechanical features of this apparatus will be given, except in so far as it is found con; venient or necessary to do so in the explanation of the operations 'of the circuits.

Referringto Fig. 1, the substation A is one of a plurality of ordinary automatic substations terminating in the automatic exchange previously referred to, and is provided with a rotary line switch whosemoveable terminals the usual talking equipment and ringer, and

also with. a calling device of a well known type which is indicated by the reference charj acter S,through the medium of which the subscriber controls the central office switches.

The line conductors 11 and 12 extend to the exchange where they terminate in the lines switchG, which may be briefly described as l or wipers have no normal positioiuand which have movements in a forward 'direction onlyi The construction ofa line switch of this type isfwell knownin the art, and its funcuon, also well understood, is to extend its as- "sociated line when calling to an idletrunk line; Incarrying out this object, a plurality of'these individual line I switches are given access to a group of trunk lines extending" to first selector switches. 'One of the'trunk lines to which the line switch C has access'is shown in the drawing as extending to the first seleotorjD, Which'is a vertical and rotary selector of the well known Strowgertype. In amultiofiice' system of the kind herein contemplated the first selectorswitchesfare usually lniown as office selectors and theselectorD in common with a'plurality of similar selectorshas] 'accesstoa plurality-of groups of-trunk lines,

' each of which group may extend to a different 'oflice orexchan'ge in the system. Some of these groups of t k lines may extend to automatic exchanges, while other group may extendto manual'exchangesl y l Atrunkline in one ofthe latter groups jissh-own in the drawing, and ooniprisesthe repeater E and the trunk gline conductors "130 and2131,which extend to the manual exchange in question and thereterminatein a pl'ug ending cord circuit-O, Fig. 2. The Y cord circuit 0 is oneofa'plurali'ty of similar cord circuits'at aB operatorszposition'in the manual exchange and constitutes the means'whereby the trunlrline shownmay be connected bvthe operator with anyone of "the manual lines terminating inthe manual exchange, One of theselines is the line of substation A, which with its associated line equipment is shown at the right of 2.

The repeater'E is an automatic impulse re- 1 peater of the general type iincommon use,

3 and in addition to repeating operating impulses to the distant manual exchange, pro vides holding circuits for the automatic switches, and thus renders it unnecessary to 1 use more than two conductors for. the inter oflice trunk line.

l F1*onithe. foregoing, itwill be understood that the operation of anolfice selector, such as the selector D, in response tothegcalling of the first digit in the telephone number of. p a line in the manualexchange, will result in 7 extending the connection from the line of. the .calling automatic subscriber to, an idle plug. ending cord circuit tin -the manual exchange. In'order to'take care of the remaining digits in the number, there is provided foreach B 'operators position a plurality of register sets as hereinbefore stated, each set being suitable for registering fall the digits in a telephone'number, with the exception I of course, of thefirstdigit which controls the 1 office selector in the v a-utomatic exchange. InFigs. 8 and 4, I have shown oneof these register sets complete. lt' comprises registercontrol switch RCS, Fig-8,theregister switchesR Rt, R and R}, Fig.4, The register control 'switcl1 BCS,-- which maybe described briefly, consists. essentially of wipers 355 and 3'56andtheirl associated-sets of bank theothers. l

- The indicating clevicebymeans of which called-telephone numbers areshown to the operator is shown in Fig.4, where it isf indi- I cated'by reference cha'racterV, and com- 7 l 100 switchboardlamps, there beingrone group of Y lamps for each registerswitchin a register set; 'ltgwill 1 be understood that the I lamps prises, essentially, a plurality of groups of have the function .of illuminating the digits of the called numbers andcausing them to standout so as to'bereadily distinguished. The digits are-preferably marked inblackon the reverse side of' a white semi-transparent surfaceand ordinarily are'not very conspicuous. But when theswltchboard lamp immee'd such character or figurewillstand out veryfclearly andfis read with greatfacility. The lamps of'the' indicating device are wired tothebank contacts which are associated several register switches of the register set shown, and are also wired-to similarl-contactsin' the banks of theregister switches of the other register sets at the position.

' As statedrhereinbefore, there area plurality of register sets providing for -the regis tration of a plurality of calls simultaneously or close together. vtlheseregistered calls are.

displayed on the indicatingdevice one after 1 10 diatelybehind'acharacter or. figure is light- 11 5 'withthewipers' 404, 424, 444 and 464 of the the other as fast as the opera tor can com-' plete the connections byplugging into the multiple jacks which correspond to the num:

hers-displayed. f In order to switch the calls over onto the indicating device insu'ccession;

which the cord circuit Oterminates.

A Ll

tion.

. the multiply connects a so-called consecution control switch is provided. This switch is shown in Fig. 2 where it is indicated by the reference character @CS, and comprises a single wiper, and a bank of contacts as shown in the drawing. The switch (JCS is mechanically the same in construction as the rotary line switch C, Fi 1, that is, its wipers have no normal position and move in a forward direction only. The

circuits, however, are changed and will be deconsist er any suifable kind of n *tercontrolledmechanism which is adapted 3 provide imp r at tlie i'ate about one per second. in order to promptly extend calls which are received at'tlie manual exchange to the reg ster sets, each cord circuitis provided with an individual rotary line switch which is maintained positioned betore an idle register set when not in use. These line switches have common access to all the register sets. The'reference character C, Fig. 3, indicates a rotary type line switch which is individual to the cord circuit 0 Fig. 2, and which has access to the register set shown in the drawings and also to the other register sets which are provided at the B operators position in The line switch C is of well known construction and function and on this accountwill not be described in detail as to its mechanical opera- The banks of the line switch C are what is known 25 point banks. The banks of the register selectors at the position are connected i multiple and a cable connects banks with one side istributing I frame, in

(heated T). F. 4;, f om which point'they l are jump; lto the various register sets in different multiple combinations as will. be

, more funy explainerl hereinafter.

Referring again to Fig. 2, there is shown in the'lower right hand corner, a trunk circuit TC. which extends to an information and complaint operatorsposition. When an incomplete telephone number is displayed, the Boperator will plug into the trunk circuit TC thercbyconnecting the calling party to the information and complaint operator. The latter operator either completes the call or advises the calling party of his error.

liiclay ATE, in Fig. 2, is what is known as the all trunk busyrelay. This relay is common to the register sets at this particular B operators position, and when operated artificially renders all the trunks extending from the automatic exchange to the B operators position busy.

At TX in Fig. 2, there is shown one of a plurality of similar keys by means of which the B operator may busy the trunks coming into her position in groups of eight.

In the dotted rectangle marked P08. 3, Fig. 2, there is shown an operators position linking key for the B operator at position 3; at P08. there is shown the position linking key for the B operator at position 2, which position is the position where cord circuit '0 is located, and at P08. 1 there is shown in the dotted rectangle the position linking key for the B operator at position 1. The position linking keys are for the purpose of permitting an operator at an intermediate position to link or connect her head set to the corn circuits of positions on either side of her position.

In the upper left hand corner of Fig. 2, there is illustrated at MB the bus-bar to which the main battery is directly connected. The conductor 2T3 illustrates the fuse wire by means of which the main battery is connected to the lower bus-bar and the conductor 274 illustrates the means by which all the apparatus at the operators position is connected to main battery, it being understood that all the battery symbols shown separately in the drawing are in reality connected to conductor 274:. a i

In the upper part of Fig. 3, there is shown the set-uppilot lamps SUP by means of which the B operator is enabled to know which register sets are in use.

In the lower part of Fig. 3, there is shown by means oft-he usual circuit diagrams the method of connecting up the first seven register sets so that they may be normally available for use, while the eighth or reserve register set is normally made busy.- When all the first seven register sets are busy, the eighth register set is then rendered available for use to take care of any call which may have come in after the seventh or lastregister set was seized and before all of the trunks were made busy.

Having described in a general way the layout of the system herein disclosed, the operation of the system will now be described more in detail, it being assumed for this purpose that the subscriber at substation A, Fig. 1 desires to obtain a connection with the manual subscriber at substation A Fig. 2, whose telephone numbers, it will be assumed. t 23456. When the receiver is removed atsubstation A, a circuit is completed over the line conductors 11 and 12 for the line relay Ll of the individual line switch C. Upon energizing, line relay 14 completes at its armature 20 a circuit which extends to the switching relay l3 and stepping magnet 15 in series to battery, and at its armature 19 connects the test wiper 26 t0 the above circuit at a pointmidway between theswitching relay and the steppingniagnetw Theoper'ation now depends-upon. whether the first se-,

lector trunk upon which the wipers of the line switch are n connection is busy or is not busy.

If the trunk line is busy, the .testcont'a'ct 31 A assoc'iated'therewi-th will have a ground potential upon itg,the switching relay 13 willbe. short circuited,and the steppingmagnet "15, which interrupts. its own circuit, will op-c jerate as a buzzer to advance the wipers 25 27, lnclu'si've, {step -by-.step 1 In search of, an 'idle trunkhne. This OPQI'ZLlJlOTLLWlll continue as longas the test, wiper QGcOntinues,tQ-engage groundedor busy i-test contacts; However,

we may assumethat in the present case when a call is initiated the selector 1) isidle, and

v the .test contact 31 thereforeis not grounded.

tical' movement. in the usual manner, and

Under these circumstances when the line-relay 14 is energized the switching relay-13'is energized immediately afterwards, with the result that the line conductors 11 and 12 are disconnectedfrom the-winding of the line relay; 14 and from ground, respectively, and are extended by way of 'arniatures 16 and "18' and their working contacts, wipers and 27, bank contacts '30 and 32,}and arlnatures and62 and their resting contacts, to the upper andlower wind-ingof the line relay 3 50 of the selector D'. c l 7 I As soon as the lineis-extendedtothe selector D as above described, the line relay50.

will beenerg'izedand will close the circuit of the 'slowacting rrelease relay 51. Upon energizing, the latter relay prepares the c1rcuit of the selector foroperation'in its eralso completes a holding circuit, extending ti on to niaintainin 'the switchin rela ener- "th e customary manner,

back to the line switch C5 as follows b ground;

1 working contact of-- armature 63 and said armature, conductor 64, bank. contact 31, test WincrQG', armature 17 i and its-working contactjwinding of the switching relay13, and the winding of the steppin magnet l5 to batr tery. It is understood that the above holding circuitis completed before the :slowacting relay 14 has hadtime to deener gize; 'In' addigize'd, the holdingcircuit alsose'rvesfto proyide: ground to themult-iples of test contact 31 and also to themultiple test contacts in which the privatenormal conductor 28 terminates in thebanksof the connectors which have access to theline of sub-statlonA, thereby guarding the connection against intrusion, in

The-calling subscriberlmay now operate his calling device S in accordance with the first digit of'the desired number. Two interruptions are thereby produced in theicircuityo'fthe linerelay 50, and the said. relay accordingly twice .deenergized momena tarlly, transm ttlngpat eachndeenerglzation annnpulse of currentthrough the slow-acting series relay: 52a nd the Vertical magnet 56 la ne s whereupon the wipers 7 0'to 7 2,in'clusive, will be-standing; opposite thelevel of bank contactsin which are terminated thetrunklmes to battery; By the operation of a jvertical I .magnet the selector'shaft is raised two steps,

'extendingc to themanual exchange.- The slo -actingirelay; 52jwhich is'energizedin I series withthe vertical magnet, retains its armature attracted throughout the yertical movement of the switch, and-upon the, closure Upon energizing '(relayr53 prepares a circuit" for the rotary magnet '54 at itslower arma= e V c ture and at its upper armature establishes a lockingcircuit for itself." At the end of the V 75" of thejvertical off-normal springs 59 completes' a circuit for the stepping relay'53.

Vertical movement of the switch, the slowa'ctingrelay 52 is deenergized and closes the I circuit of fthe rotaryirnagnet, which is thereupon, energized to advancethe wipers'ZO to v72 inclusive; into engagement ,withithe first setofbank contacts in the "level"oppositev whichthey wereraised. The rotary magnet '54 also breaks the locking circuit for the stepping relay 53 which accordingly deener- .gizesand breaks the circuit of the rotary" i magnet, which thereupon deenergizes also,

and again closesits interrupter Contact. Theoperatlon now depends upon whether the trunkline with which the Fwipers are connected is busy or isnot If the trunk line islbusy the test contact'associatedtheref" i n V with'will begroundedand thestepping relay i 53 will be energized over a circuit which eX-f 1 tends by wayof'the testwiper 71, armature J61 and1itsresting contact, off normal springs" 59, interrupter contact of the rotary magnet,"

and thewinding of stepping. relayv 53 to battery, The stepping relay will therefore again close the circuit of' the rotary magnet 54 whichwill operate to rotate the switch wipers into engagement withithenext set of bank contacts. This operation in" which the I stepping relay and the rotarymagnet are alternately energized "and deenergized will conidle trunk line and when therefore the test wiper arrives at test"contact 74clland the rolay. 53 will not again be operated, but instead the switching relay 55.. which heretofore'has been shortcircuited, will be energized by current flowing-over the following path grounded conductors 64c, winding of the switching relay 55, off normal' springs 59, interrupter;

contacts of the rotary magnet .54, and: the .7

windingof the stepping relay 53' to battery. Owing to the high resistance of' the switching relay 55, stepping,relay 53 is not operated.

.Upon energizing,-relay 55 disconnects the in coiningline conductors from the winding of.

the line relay 50 and extends them by way of line relay aho 75, trunk conductors 76 and 78, and normally closed contacts of; the reversing relay 100, to "he upperand lower windings oi the 01 of the repeater a qlVhcn the line is Z-IEGIlClQCl to the repeater re explained, the line relay 101 is enand closes a circuit for the slow act Upon energizing, re-

g circuit extending back to the selector 1) and the line switch (3 as follows: ground, armature 112 and its working contact, conductor 77, test contact 4, test Wi per 71, and the armature 61 and its working contact to conductor 6 1, where it joins the previously descr'bed holding circuit extent" hack to line switch G The above described c'" serves to maintain relays :I d 13 encrgzed throughout the duration of the connection.

in addition to closing the holding circuit 'for the automatic switches C and D, the rela of he repeater E prepares :1 cl 'cuit ts armature 115 for the slow acting relay u; closes a circuit at its armature 11% for relay 104i; and at its armature stes circuit for energizing the line of the cord circuit (),-Fig. 2 over llowing path: troin ground by way e normally closed springs controlled by ire'118, working contact of armature 113 and said armature, conductor 130 armature 214i- 'is resting contact, upper left hand Winding of the repeating coil of the curd circuit O, norma. closed springs con- Ly armature and upper winding ne relay 200 to battery. Upon enerune relay 200 causes the energization o. ill {I hi release relay 205. The latter relay up ergizing connects ground at armature 23 lower windii'ig of the line relay 206 so I; e line relay may he maintained energi ed by a bridge at the repeater E.

i c HOW to the repeater E, the relay energized from ground at armature 's ow to pull up so to allow time ;he line relay at the'cord cirthe upper talking conductor as 1 On energizin g, relay 104 disconrouud from the c ilductor 130 and the l energizing circuit 01? the line relay 200 circuit 0. At armature 120 and contact, relay 10% connects trunk conductor 7?; at 1 and its working contact closes ougli the polarizing winding of lzed relay 105 and at arms 3.18 and its Wei c actors 130 and c the following path: mire 113 and its i-rorkino con ecu, work'ng contacts of armaand said. armature, armature 116 and re; ing contact, lower winding of the electro-polarized relay 105, normally closed springs controlled by armature 108 of relay 100, right hand winding of the impedance coil 106, and working contact of armature 111 and said armature to'conductor 131. By the closure of this bridge across the trunk line a circuit is completed for maintaining energized the double wound line relay 206 of the cord circuit 0. I e

When the line and release relays of cord circuit O'are operated, as above explained, the latter relay at armature 232 opens a point in the circuit of the supervisory lamp SL and at itsworking contact connects ground to conductor 257. At armature 233, relay 205 prepares a point in the inipulsing circuit; at armature-235 and its working contact connects ground to the lower winding of the line relay'206 as previously explained.

It may well be mentioned at this point that the register selector C is a preselecting switch, and it is assumed that the switch C has preselected the register set shown in the drawings in Fig. 3. The method of preselecting an idle register set will be fully described hereinafter. When relay 205 pulls up it closes at armature 2 34'an energizing circuit for relay 204 as follows; from ground by way of armature 224 and its resting contact, lower winding of relay 204,,working contact of armature 23andsaid armature, armature 222 and its resting contact, resting contact of armature 218 and said armature, conductor 301, wiper 301, bank contact connected to terminal pin 305, jumper 308, terminal contact 311, conductor 372, armature 331 and its resting. contact, terminal 379, jumper 380, terminal 381, armature 334 and its resting contact, and winding of relay 325 to batter Y When the above traced circuit for relay 325 is closed, said relay energizes and at armature 338 and its resting contact opens a normally closed short circuit from around the relay 323, atarmature 339 and its working contactcloses a circuit for operating the time switch P, and at armature 3 10 and its resting contact opens one of the several energizing circuits for the relay 392.

Returning now to the cord circuit O, relay 20 i is energized over the previously traced circuit and at armature 227 and its working contact prepares a point in the circuit for'the call lamp CL, at armature 228 and its working contactprepares a circuit for relay 201, at armature 230 and its working contact closes a locking circuit for itself through arniatures 220and 217 to grounded conductor 257, and at armature 231 and its working contact connects direct ground to the release trunk conductor 301 to guard the seized register set from being seized by other register selectors such as C. At armature 229 and its resting contact, relay 204 opens a point in the circuit for the busy relay 202, so

I I layfwi'll not be energized from ground at armature 236, and at its workingc'ontact; prepares the impulsingfcircuitextending 'over conductor 303 to the register set. Everything is now in 'read'ness' The subscriber will now" operate his calling device in accordance with the digit 3, which willicause-line relay llof the repeater E f fall back a corresponding number oftimes, we 'w esu s i he p r ion of slow rel'ay 1103 for placing'a direct bridge acrossthe trunk conductors 130and 131. The opera tiono'if line relay 101 causesthe circuitl'ofthe' line relay 206 to be: interrupted alike number of. times. Each time linerelay 206 falls back an impulse is transmitted to stepping "magnet. 461 over; the following; circuit ground, a maturese and its resting'eontact, working contactpf arrrlature'233Qand' said i J erma ureia ure 22 .1e d. t 'wo' king 0 I tact, impulse conduetor 303', wiper 303, Fig.

I 'ated, In joperated position, relay 327 closes a'circuit'fortheslow acting relay 328, which 7 ing circuit is thustransferred to conductor '361iwhich' extends to the stepping magnet i i-6 i ter switch R moved oh-normal *The cirbank contact engagedfby wiper 303, terininal pini306, jum r 309,- termin'al contact 312,: conductor 3T1, winding ofrelay' 327,

wiper 355 Of th r gis e co r sw R 5, conductor 360 stepping magnet 461 of ther 'rigisteriswitch Rlto lpjatteryl; By the operac 7 vtheregister switch R? is a'dvanced three steps tipn of'th S BPP g' agn t-4:6 W p r 64 and is brought to restin engagement with the th rd ,QQntactjv-jo f its;bank; l The, slow, acting i'ellayf32 7 isj energized in series with stepping magnet; 461 and retains its armature 344 ate tracted while the said magnet" is beingoperis held in operated position also duringthe operationof the first register switch; Q After the last impulse has, been transmitted, the

slow-acting relay 327 will denergize and break the circuit of relay 328 at armature I 344. Since the latter relayis slow-acting, however, a cireuitwill be'closed for an instant] which, extends from the grounded armature 344 by way of its resting contact, working contact of armature 345 and'said armature, andthe winding of-stepping magnet 359 of the register control switch ROS tobatteryv One impulse is thus transmitted to thesteppingmagnet 359, and the wipers 355 and356 areiadvanced one stepintoiengagem'ent'with the second contactsin their respective banks." The advance-of wiper 356 is of no eiiect, but when wiper, 355 moves from its first contact to the second, the operat 441 of the register switchR .It maylwellbe mentioned at this time that relay 323 was energized as soonas the regiscuit for relay 323 may be traced as follows: from ground thru low resistance'winding'of energized 'in thiscircuit on account of the p v for the transm1ssionof the second ser1es of impulses.

stepping magnet 441i is'thus operated to ad lenergizedduring the transmissionjof the sec the stepping switch R the last operation messes 323' conductor 405,"oii-normal springs 463,

winding;ofjreleasemagnet 462 tobaitteryi The relay 322ai1d release magnet 462 'are'not at itsf'working Contact; Relay 324 however magnet 441 of the registerswitch R2. The

"relay 322, winding of high iresistance relay I ,7

hi'ghresistance of relay 323. JAjt' armature 1 364, relay 323 removes groundirom conduc tor 376 and'preparesa'ci'rcuit for'rel'ay 324; I

Vance its wipers 444 four steps and'the wiper is brought to rest in engagementawith the V fourth contact in its banks.

,7 The slow-acting relays 3 27 V328 are end series of impulses the same as during the gfirst, and when the impulses ceasev another impulse of currentis-transmitted' to the step o'in ma net" 359' oi the re ister control? 1 i h l. b g i 2: v i l V A I switch ROS, thus advancing the wipers355" and 356' another step, and transferring the 'operatingrcircuit by way ofconductor, 362 to I It willnot benecessary to consider 'in de- 1 tail'the manner in which the register switches R and R are operated. i When the digit 5 is called Theseri'es of 'siX impulses which results 'magnet 42 1 of the register 1 a series of five impulses are trans-c mitted'tothe stepping magneto 421' of. the

V. no steppmgmagnet 401 oithe reg ster sw1tch= from the'calling of the final digit thus causes 5 '7 the operation of the stepping magnet 401 and'the wlper 404iis advanced. into engage 5 Inent w th the sixth 'jc ontact in--its' bank.-

The stepping magnet 359 ofthe register con- 7 I a trol switch is given anotherimpulseof current also at theend of the last series of impulses and wipers 355 and 356are advancedone'mor'estep/ of the register conj j trol switch RG55 wiper .356 is b-rought'iinto engagement with'the fifthlcontact in its bank 1 sulting in" the'energization of relay 326.

and ground is placed on conductor 369, re-

Upon attracting its armature 342, relay' 326 stops the operation of the timing switch P, 1

while at armature 3,41 ground isconnected by way of armature 330for lighting theset-up lamp. 370 thereby indicating'to an operator that a call has been set up on the third register set. Relay 326 at armature 3&3 and its resting contact removes a short circuit from around the relay Y329 and at its working contact closes a circuit over the conductor 37? for energizing the "clay 281 of the switch CCS in Fig. 2. Armature also removes ground from conductor 37-6 thereby removing ground from the bank contact in the switch CCS which corresponds to the register set shown in Fig. 3. i

The consecution switch CCS has all its bank contacts normally grounded over conductors such conductor 376 and as soon as relays such as relays 326 and 323 are energized ground is removed from the bank contact corresponding to the register set in use.

Responsive to the energization of relay 281 overthe above traced circuit, said relay at armature 282 and its working contact closes circuit for operating the stepping magnet 283 by way of the grounded bank contacts of the .consecution switch CCS. The stepping magnet 283 energizes from ground on the grounded bank contacts encountered wiper 230, interrupts its own circuit, anc continues to operate in a buzzerlikc m nner until the wiper 280 encounters the bank contact connected to conductor 376 from which ground has been previously removed. Responsive to the wiper 280 coming into engageinent with the bank contact connected to conductor 376, a circuit is no longer closed for the stepping magnet and a circuit may now be traced for energizing the high resistance relay 329 Fig. 3, as follows: from ground winding of relay 32 9, armature. 332 and its resting contact, conductor 378, conductor 3%,

bank contact individual to the register set shown in Fig. 3, wiper 280, working contact of armature 282 and said armature, inter rupter springs of the stepping magnet 283,

'3 and winding of steppin magnet 283 to bat tery. Due to the high resistance of relay 329 the stepping magnet'283 is not energized over the above traced circuit. Relay 329, however, is energized and at armature 353 connects ground to conductor 373 for ligl ing the call lamp CL over a circuit as follows from ground, working conta ct of armature 353 and said armature, conductor 3T3, terminal 313, jumper 310, terminal 307, bank contact of the register selector C, wiper i, conductor 304i, armature 227 and its working contact, winding ofrelay 211, resting contact of armature 219 and said armature, armature and its resting contact, call lamp CL to battery. Relay 21 1 is energized over the above traced circuit and at armature 24.8 disconnects the supervisory lamp SL. Other calls may be registered on the other register sets at any time now and when the registrzu 5 tion. is completed the set-up-pilot lamps, such as lamp 370; corresponding to the register sets in use will be lighted, but thishas no etl'ect onthe consecution switch CCS, which makes no further movement until the call on the third register set has been disposed oi. Relay 329 is'the relay which switches over the registered call to the lamps of the indicating device and the manner in which this is done will now be pointed out, it being recollected that the wipers 464, l l-l, 42 i and 4104, are now resting on the Src, 4th, 5th, and tith contacts in their respective banks. When the armatures 34-8 of relay 329 are operated, ground is connected to concuctors 3&9 to 352, inclusive. It follows, therefore, that with the conductors 349 to 3:32, inclusive, grounded the conductors 176, 455, 34.3, and lie will also be grounded. l ese latter mentioned conductors extend to the indicating device V and terminate in the lamp of the first group, the gi ll lamp of the second group, the #2,:5 lamp at the third group, and the #8 lamp in the fourth group, respect vely. The other side of the lamp is connected to battery and the lamps mentioned are accordingly illuminated.

The manner in which the operator l11ll (lles the call thus displayed before her will now be considered. When the relay 329 in ig. 3 pulls up and closes the circuit for displaying the registered number to the operator, it also closes at its armature 353 the circuit for the call lamp CL in the cord circuit 0. The lighting of the lamp CL which is individual to the cord circuit C is lighted simultaneously with the lamps in the indicating device V, thus enabling the oper-, ator to know which one of the cord circuit-s is being used by the automatic subscriber, whose wanted number is at this particular time being shown on the indicating device. Having observed the 3456 and knowing by the lighting of the called lamp CL that the cord circuit C is the one in use, the operator will test the multiple jack of the line with the tip of her plug in the usual. manner in order to find out whether or not the line is busy. If the line is found to be in use, the operator will hear the well known busy click, and will immed'ate ly operate her busy key BK. The two keys indicated by BK are in reality one key and have been shown as two keys so to simplify the drawings. By the operation oi the upper busy key BK the stepping magnet 283 of the consecution control switch CCS is energized. A circuit is also closed through the lower busy key BK from ground at said key, through working contact of armature 242 of relay 209 which was previously energized in parallel with relay 211. armature 243 and its resting contact, winding of relay 202 to battery. Relay 202, immediately energizes and locks itself at armature 221 to the grounded conductor 257. Relay 202 at t lilo lib armature 222 removes ground from the re-" lease trunk conductor301, and atarmature "223 and its working contact connects the busy tonethru the condenser 259, through armature 220 Opens the locking'circuit' of relay 204' which thereupon deenergizes, at

the lower right'hand winding of relay 208 to battery. The busy'tone is now transmitted to the call-ingxsub'scriberin the well known Bytheremoval of ground from the release trunk conductor. 301, the short circuit around relay 324 ,ihas been removed, and said relay energizes overa circuit from round at ar- .jmature 364in series'with relay 325. 3 Relay 324 upoirenergizing closes at armature 336 and its workingcontact a circuit for releas-' ing the "register 'controlswitch, the; time switch 'l,;and all'of the register switches R? to R inclusive, as follows: ground through the low resistancewinding of relay' 322, armature "3,36. and its working contact, ofi" normal 'springs 357 10f, the -.register control switchRCS,release'magnet 358 to battery;

to the resting contact of'armature 347 and said armature, ofinormal springs 367 ofthe ltime switch T, releasemagnet 366 to hat tery; to conductor 405; from whichzpoin't ground is connected tothe release magnets 402,422, 442 and 462 through oil-normal contacts 403423, 443 and 463, respectively. The register control switch RCS, the time switch T,'a'nd the register switches R tolt inclusive, release in the well known manner. Relay 322 is energized. in series wlth the .variousrelease magnets-and at armature -334and1its working contact connects ground to the conductor 372 thereby rendering the register" set busy until the apparatus inthe,

set has been completely restored to normal.

WVhe'n relay 324'operates its"ar1nature 336,

' relay 323 is'short circuited and'after an in-v terval, said relay deenergizes, Relay'323 upon deenergizing opens at armature 364 the circuitof relays 324 and 325 which there upon deenergize. "At armature 364 andits "resting'contact, relay 323 connects ground to conductor 376'so-as to busy the register set in the consecution control switch; Relay 5o 325 deenergiz'es before relay 324- thereby maintaining at arniat'ure 338 the short circuit around relay323; .As soon as all: of the register switches, the register control switch and the time switch T have been returned'to" normal, the circuit of relay 322 is opened at p the various off normal contacts. In case any one of the abov'e'swi tches did not properly release,relay 322 would be maintained energized, thereby maintaining the register set busy. 'The relay 326 was also deene'rgized responsive to the release of the register control switch thereby causing relay 281 of the switch CGS to deenergize' Relay 329'is again short circuit'edand said relay releases and dls'connects ground from conductors349 10 ,manner and need not he explainedin detail'f a 352, inclusive. A1101? the apparat s shown in Figs. 3and. 4, ,have beenretur'ned to their normal positions, andfare available for use' n another call.

then the operator; releases busy key i BK, thestepp'ing magnet 2830f the consecu- I tion control switch CCS-deen'ergizes and advances the wiper 280 on'estep gc-j p The reason for holding stepping magnet V283 energized during the timethe busy key is depressed is to prevent the operationof the. switch CCS thereby"preventingithe op p V eration of busyrelay's in othercord circuit-s5 when calls onlthe other'cord circuits'are wait ingto'be displayed i in the present case is-thejackJ As soonas the plug is inserted 'into' 'the jack, a circuit is' completed for-thesleeve relay 210 in Series I with the cut o't'f, relay 261 of the called line, i and the latter relay is energized to clear the I V a i Assumingshowever, that the line is found to be idle, the operator will at 'o'nce'insert the plug B into the jack of the wanted line, which line of itsnormalbattery and'ground connec 7 tions in the usual manner, Relay 210 is'en ergized also and at armature 240 prepares a] clrcult for the superv sory lamp-SL,-jat ar V mature 241 opensthecircuit of relay 209 at its resting c'ontactand at its working con- I tact closes a cir'cuit for-energizing relay'20l,

at armature243 andiits're'sting contact opens the circuit, of the busy relay 202, at armature. I 244' and its restingcontactr opens the circuit of the call lamp CL,-at armature 245'andfits working contact'connects ground to conducs "tor 279, at armatures 246' and 247 and'their working contacts completes a ringback cir cuit for transmitting ringing induction to the calling subscriber, at armature 247 and its,

workingrcontact connects generator to we called line, and at the resting contact of ar mature 247 disconnects the operators head-- set. Ringing current is now connected to'the 7 called subscriber; over the following i'path:

from'generator, winding of relay 212, restingcontact ofvarmature'256 and saidarmature,

working contact oi arm'ature 247 and said armature, tip ofplug P, tip of jackjJ through the called subscribers ringers, back over they ring conductor of plugiP, armature 250 and its resting-contact,resistance 259, 't'o'battery;

,When the sleeve relay'was' energized itcloseda circuit 'forenergizingrelay 201as foli lows: grounded conductor304,armature 227 and itsworkmg contact, armature 241 and'lts workingcontact,=work1'ng contact'of arma- Iture' 228 and said armature, normally closed springs controlled by 'armature 217, and

winding of relay 201 to battery; Relay 201, v g

thus reversed.

armature 219 prepares a substitute circuit for the call lamp CL which includes the interrupter I for fiashingthe call lamp CL in case the operator removes the plug P from the jack prematurely. v

Responsive to the removal of ground from the conductor 301 the shortcircuit aroundrelay 324 is removed and said relay energizes in series with relay 325. The operation of the relay and the release magnet-s of the various switches in Figs. 3 and at are now the same as previously described and the apparatus is restored to normal. The register control switch, the register switches, and the consecution control switch are now in readiness to be used for another call.

Referring now to the cord circuit 0, it has. been explained how the connection has been completed to the line of the called station A, and how ringing current is projectedover the called line to signal the subscriber. During the ringing operation a tone is induced in the lower right hand winding of the repeating coil of the cord circuit O by means of which the calling subscriber is advised that the called subscriber is being signalled. Vi/ hen the called subscriber answers,the ring cut-oil relay 212 energizes in a well known manner and closes a circuit at ar1nature249 for relay 213 from ground over the sleeve of plug P and jack J. Relay213, upon energizing, at armature 251 completes a locking circuit for itself and at armatures 250 and 256 and their resting contacts disconnects the generator from the called line and at their working contacts connects the line of the called subscriber to the right hand windings of the repeating coil thereby completing a talking circuit for the called subscriber which includes the lower and upper windings of relay 208 and the right hand windings of the repeating coil. Relay 208is energized over the calledsubscribers loop and at armature 23S) completes an energizing circuit for the reversing relay 20?. In energized position, relay 207 reverses the trunk conductors 1'30 and .131 as regards their connections with the windings of the line relay 206, and the direction of current flowin the trunl: line is Due to the reversal of current flow the trunk line the polarized relay 105 in the repeater E is now energized and at armature 119 and itsworking contact completes a circuit for energizing the reversing relay 100 of the repeater E. Upon energizing relay 10-0 reverses the trunk conductor. 76 and 78 as regards their connections with the winding of the line relay 101, and the direction of current flow in the calling line is thus reversed. This operation maybe used for operating a meter or for similar purposes, and is provided in accordance standard practice, although it is of no utility in the particular system shown herein.

The required connection having been established, the subscribers may now converse as desired. lVhen the conversation is finished both subscribers will hang up their receivers, and the replacement oi"; the receiver at the calling station A causes the decnergization of the line relay 101 in the repeater E and also the release or" slow acting release relay 102. Relay 101 upon releasing, completes a circuit for relay 103 so that when relay 102 deenergizcs, ground is removed from release conductor 7'? thereby allowing the automatic switches to be restored to normal in the usual manner. The bridge across the trunk conductors 130 and 131 being broken by the deenergization of line relay 101 of the repeater E the circuit of the line relay in the cord circuit O is thereby opened whereupon said relay deenergizes. After a short interval of time the slow acting relay 205 also deencrgizes and closes a circuit for the supervisory lamp SL at armature 232, and at the same armature also opens the circuit of relays 207 and 201 which thereupon deenergize. Relay 205 also removes ground from conductor 279 and prepares a circuit for relay 203. hen the slow-acting relay 102 of the repeater E deenergizes it opens at armature 114 a circuit for relay 104 and at the same armature by way of its resting contact substitutes auother circuit for energizing relay 104 as follows: from ground by way of armature 245 and its working contact, conductor 2T9 lowor winding of line relay 206, normally closed springs controlled by armature 268., lower left hand winding of the repeating coil, resting contact of arn'iature 216 and said arma-- ture, conductor 131, resting contact of ar-- mature 114, and winding of relay 101 to battery. Relay 10 lenerg'izes over the above traced circuit but due to its high resistance, the line relay 206 is not energized. At armature 120, relay 10 i connects ground to the release conductor 7" thereby maintaining this trunk circuit busy to the automatic switches in the automatic otlice as long as the plug P remains inserted in the jack J.

The automatic switches now have been re leased, a disconnect signal has been given to the operator, and the trunk line in use has been made busy pendingthe pulling down of the connection. When the operator observes the lighted supervisory lamp SL she will remove the plug of the cord circuit 0 from the jack and relays 210 and 213 are deenergized and restored to normal. By the falling back of relay 210 the circuit of the supervisory lamp SL is broken at armature 2% and at armature 245 ground is removed from conductor 270 thereby permitting the relay 104 of the repeater E to deenergize and remove ground from the release trunk conductor 77. All the apparatus has now been restored and is ready for use in handhng'another call. 4 e

Certain details of the syste n w ll now be lained which it was not-convenient to '0 into before, and thefirstthing whichwill be considered is the preselecting operationot the registerse'lector C. For this purpose, it will be assumed that the cord circuit V0 is idle,

' that the wipers or the register selector switch,

C, are standing in the position shown in the drawing, Fig, 3, and that the register set' associated'with these bank contacts becomes busy. Under the above conditionsa circuit can now be traced to the lower winding of the differential relay 203 of the cord circuit 0 over the following path: "from ground on the bank contact associated with the busy register set, wiper 301,'arn1ature 218 and its resting contact, resting contact of arniatures 222 andsaidarinature, armature 23 i and its restingcontact, and lower winding of relay 203 tobattery. Relay 203 energizesover the above traced. circult and at armature 225 maintains the above traced circuit independent of armature 23lso that iifthe cord cir cuit should be taken into use, the circuit of the relay 203 would not be opened by the operation ofthe release relay205 At ar nature 22 i and its resting contact, relay 203- opens the energizing circuit tor frelay 20 1 so that relay 204 cannot energize until after an idle register set'has'been selected. 'In

addition to the above, relay 203 at armature 224 and its worklngcontact connects ground to conductor. 302 therebyclosing a circuit for the stepping magnet 32001? the register selec.--

tor C so that said stepping inagnet will operate in a, manner of a'buzzer until ground is removed from conductor 302. Although relay 203 is a diiferential relay the resistance inserted in series with the upper winding will not permit the relay to be deenergized when armature 122 i connects ground to the upper winding of said relay. A's-long as the wiper 301 encounters grounded contacts of busy register sets, relay 203 Wlll be-nia ntained energized'through its lower winding; It will now'be assumed that an idle registerset is reached and when the test w1per'301 engages the bank contact associated therewith,"said contact will not begrounded, but will have" a battery potential thereon. Under this condition the circuit to thelower winding of re: lay 203 is opened. Due to the current flow through the upper winding of relay 203,niagnetic flLlXWVlll be built ,ip in opposition to the magnetic flux created by the circuit through the lower winding and when the flux reaches a certain pointsaid relay is quickly deenergized, thereby removing ground from conductor 302 and stopping the operation of the register selector on the idle register set.

In case the cord circuit O should be seized and the calling subscriber should start diallingbeiore. an idle register. sethas been seized the busy relayi202 weuldbe energized for transmitting a busytone-to the calhng subscriber;

The circuit traced as follows: ground from armature 236 and its resting contact, working contact ofarma'ture 233 andsaid armature, armature 229 and lts restlng contact, armature 2&3 and its resting contact, {and winding otfbusy relay 202 to battery. p 7

Another feature oithei-nvention which is more orlessjrelated to the'toreg'oing is'the novel means by 'which the auteinatic'trunk, which is associated with' thecord circuit JO, is made busy during-the tiine'the register. selector is hunting-for anidle register setJ It willihe remembered tliat relay 203was energized to control the huntingoperation'oi the register selector. Relay'203 upon energiz ing, at armature 226 connects'ground to con-I for energizing relay 202 maybe ductor 279 from whence it extends by way, tl l 'd' t tl l" l 206 or re ouer wintin o 716 me is ay I 7 normally closed springs controlled'by'iarnia L ture 238, lower left hand windingoi the re- 6 peating coil, restingcontactof armature 216 v and said armature, conductor 13l,resting contact ot armature 11 4 and" said armature, and winding of relay -1O lto battery. The, line relay 208-111 the cor'dfcircuit is not energized over this circuit on accountofthe high resist: ance of relay- 10a but the latter relay, how-f ever, energizes and at armature connects ground to the release trunk conductor 77 thereby. rendering the repeater cause of improper dialling by the callingsub scriber, or failure of seine switch to-function properly are notfcolnpletely registered; It villbe understood that in the'ordinary operation of the system, a call is displayed to the operator by the energization ot're'lay329 at the proper time under-control of the consecu f tion 'CQIItIOl SWItCll The energization of relay 329,- however, s contingention :four

series of impulses being i1lllSHllttfltlllOUgll the reg ster control switch RCS, which causes the wiper 356, to engage the tth' contact in itsbankto ground conductor 369 i and it will be appreciated, therefore, that if less than 7 four digits are registered, relay 329 will not ordinarily. energize, and the partiallyregisterednumber will never be displayed to the operator. Experience has shown that these incoinpleted calls are/a fruitful source oi trouble, s1nce each such call, occupies a regishis receiver, without giving the'operatora signal atany time; In-order'to' eliminate the i ter set until the calling subscriber hangs up i i NJ difliculty pointed out, thetiming switch P is provided, and this switch is adapted to bring about the display of any call after a certain time interval, regardless of whether all of the 1 digits in the called number are registered or not. It will now be assumed that a call has arrived at the register set shown in Figs. 3 and 4; and that relay 325 has been energized. /Vhen relay 325 pulls up a circuit is closed for the stepping magnet 365 of the timing switch P at armature 339, and the timing switcli begins to operate under control of controlling the conse'cution control switch CCS and incidentally the relay 329 so that whatever digits, if any, have been registered, are displayed tothe operator. It will be remembered that relay 328 is operated once for each series of impulses and said relay at armature 346 opens the circuit of the stepping magnet'365, and at armature 347 closes a cir- 1 cuit to the release magnet 366. The timing switch P is, therefore, released each time a digit is dialled by a calling subscriber and therefore it would be ten seconds after the lastdigit had been dialled bythe calling subscriber before the time switch P would complete the circuit for relay 326. It is intended that the mutilated calls will be extended by the operator to a complaint or trouble operator by'plugging into a trunk line provided for this purpose in order that the regular operator may be free to confine her attention to handling the regular traffic.

Another novel feature of the invention which relates to the foregoing is the circuit arrangements by means of which the ringing current is cut off and a ring back tone given to the calling subscriber when a calling subscriber is connected by means of the cord circuit to the information and complaint operators trunk circuit- .such as illustrated at TC Fig. 2. Assuming that only a partially registered call has been displayed to the operator and that the cord circuit 0 is the cord circuit over which the calling party is endeavoring to establish a connection, the operator will insert the plug P into the jack J which is used for handling special calls of this nature. Responsive to the insertion of the plug P into the jack J a circuit is closed for energizing relay 210 of the cord circuit 0 and relay 266 of the operatorstrunk circuit TC in series over the sleeve of the jack J. As soon as relay 210 is energized a circuitmay be traced for energizing the ring cut-ofl relay 212 as follows: from battery through the right hand winding of induction coil lC, common conductor 270, working contact of armature 26S and said armature, conductor 271, tip of plug P, armature 2 17 and its working contact, armature 256 and its resting contact, and winding of relay 212 to generator. Relay 212 is energized over the above traced circuit and closes a circuit for operating relay 213 as previously described. Ringing current is thus cut off. it will be noted, that interrupted generator is connected to the left hand winding of the induction coil 1C and therefore a circuit may be traced through the left hand winding of induction coil 1C over the previously traced circuit to armature 247 from where it extends to armature 2&6 and its working contact, condenser 259. lower right hand winding of repeating coil, and lower winding of relay 208 to battery. Ringing induction is now transmitted to the calling subscriber through the windings of the repeating coil in the well known manner. lVhcn relay 266 in the trunk circuit TC is operated, it closes a circuit for lighting the call lamp L, thereby notifying the trunk operator that a call should be answered. The operator upon observing the lighting of the lamp L operates her answer key AK thereby connecting her headset to the trunk conductors 271 and 272. The key AK also closes a circuit for energizing relay 265 which opens the circuit for the lamp L at its upper armature and at armature 268 also opens the ringback tone to the calling subscriber. The information and complaint operator may now converse with the calling subscriber in the usual manner and take the necessary steps to either complete the call or inform the calling subscriber of his error. It can he plainly seen from the foregoing that the same circuit which cuts off the ringing current also applies the ringback tone to the cord circuit O for transmitting the tone to the calling party. I

Another feature of the invention relates to the method of multiplying the register sets, which are only eight in number, to the register selector banks. The multiplying of the register sets in the banks of the register selectors is accomplished by the aid of an intermediate distributing frame. The banks of all the register selectors at the position are connected in multiple and a cable connects the multiply connected banks with one side of the distributing frame, where the cable is terminated on twenty-five sets of terminal pins.

In the bottom half of Fig. 4;, the distributing frame is indicated by the reference characters I. D. F. The lower row of twentyfive terminals are the terminals for the release trunk conductors coming from the bank contacts of the register selectors. The release trunk conductors of the eight register setsare connected to eight terminal contacts on the other side-of the PD. F. Although only the release trunk terminals are shown, it will be.

understood that there arethree terniinalsto each set; 'As'the regjcsterselectors have ac.

cess to only eight register sets the terminal pins are.dividedintothree groups, thefirst group comprising terminal pins 1 to-8, inclusive,'the second group 9 to 16, inclusive, and'the third group 17 to 25,'inclusive. The

V eight register sets are cross connected by umpers at the'l; D. E, to the terminal pins I numbered 1 to 25, inclusive. The number 1 register set-is inultipled to the #1,?513, and 19 terminal pins the number 2 re lster set is multipled to the #2, #9 and #22 terminal pins, thenuinber 3 register set is multipled to #8, -"-14.-, and #1? terminal pins, the.

the number 4 registersetis multipled to thei -+41,

#10, and #QOJterininal pins, the number5- register set is multipled to the #5, #15, and

#23 terminal pins, chef/ 4:6 register set is multipled to the #6, #11, and #18 terminal pins, the number 7 register set is inultip'led'tothe .,+j:7 and #21 terminal pins, and the number 8,register ismultialed to the 12-and #Qd terminal pins. vThe eighth, sixteenth,

and twenty-fifth terminalpins are dead and are crossconnected insuch a manner that they" provide stopping" positions for the register selectors in case all eightregister sets become busy. With the register sets multip'led at the I. D. F., in the manner pointed out itneces-i sarily follows that each of the register sets .is. accessible to a registerselector at a pluf rality of points in ts bank. Although the corresponding bank contacts of all the register selectors atthe positionare connected in a straight multiple, the cross connections at the l. D. F. divides each bank into a plurality of groups of bank contacts and provides a slip between the bank contacts in eachof the groups. Considerable saving 1s effected by 'miulti 'iling the register-sets at the I. F, be-

cause it permits changes such as varying the number of register sets to be used or tor 9 varyingthe slip in the multiple between bank contacts to be readily'and easily made at the same time keeping the multiples straight be- 1 13 tweenbanks. I

The slip in the register selector bank contacts between groups is providedfor the purpose of preventing all the idle preselecting register selectors from preselecting the same idle register set on their next operation in case they had previously selected the same register 25 set. For example, itwill be assumed that there is a register selector in engagement with the multiples of the first register set of the different groups that is, a first register selector 'is'in engagement wi'ththe #1 bank contact in the first group of its associated bank, a sec-. ondregister selector is in engagement with the'cfitlffl bank contact in the second group of its associated bank, and a third register selector is in engagement with the #19 bank contact inthe third group of its associated bank.

Ass'umingnow that the #1 register setbecomes busy, ground is connected to the mul tiples of said set causing all. of the-register selectors which are-in engagement therewith to start hunting topre'slect another idle h,

registerset. The said first register selector willstepone step into engagement with the Qndbank contact or the multiples of the #2 register set, the said second registerselectoc will step one step into engagement with the 14th bankc'ontactor the lIlLlltlPlGSOfilhG #3 register set,,and the said third 'selector will step one step into engagementwiththeQOth bank contact or the multiples ofthe #4 register set. It can be seen from the foregoing that each register. selector, which have their Wipers,positioned in different groups, selects diil'erent register set for each corresponding step when they are initially. started frommul l tiple's of the same register set.

Having explained in detail how the bank contacts oi the register selectorsareconnects ed in a slip multiple meansof jumpers at the I. D;., when-eight registersets aregto be used, Iwill newbriefly'pointouthow. the bank contacts'of the register selectors .are,

cross-connected to. the register sets at, the

l. D. F, when a variable number oi -register sets isto be used at an operators position.

The following is a'chart. showing the slip multiple} arrangement for cross-connecting the bank contactsoi' the. register selectors at s the l. D. E, to the register sets 1 Chart I v Register sel. BankContact No.

Reg. sets Beg. sets Dead Dead Dead 7 in Dead ouo uma ocofi uicp seamen-us Masaien GOD-OrBlO #3 Dead Dead Dead 7 Dead Reg. sets Reading from left to right, the left hand column indicates the numbers of theregister selector bank contacts which are connect-ed to V correspondingly numbered terminal pins on the I. D. F., and the other columns indicate the number of the register sets-which are multipled to the seleotor'bank contacts in the following manner. In order to explain the chart it will be assumed that only six register sets are tobe used at an operators posi-,

, terminal pin. contacts the tion and therefore only the first and fourth columns may be considered. The #1 bank contact is multipled to the #1 register, the #2 bank contact to the #2 register set, the #3 bank contact to the #3 register set, the #4 bank contact to #4 register set, the #5 bank contact to the register set, and contact is connected to a dead in the next group of bank bank contact is multipled to set, the #3 bank contact to the #4 register et, the #9 bank couta rt to the #6 register set, etc. In case 5 or 'iregister sets were to be used at an operators position. the register sets would be cross-connected at the I. D. F, in an obvious manner. It can plainly be seen from the foregoing that in order to change the number of register sets to be used or in order to change the slii multiple it is only necessary to change cross connections or jumpers at the I. D. F.

There are provided in the instant case eight register sets per operators position. Seven of which are normally available for use while the eighth is artificially made busy. According to another feature of the invention when all seven register ets become busy, a circuit will be completed. for energizing the all trunk busy relay ATE to busy the operatofls position." A still further feature or" the invention which may be described in conjunction with the preceding, relates to the means for rendering the eighth register set idle so that it a call should come into the operators position before said position has been made busy, the call woulc seize the eighth register set and the connection would be completed in the same manner as previously described.

Referring now to 3, the first seven register sets have their terminals 379 and 381 connected by a jumper 380 and have their armatures 340 connected by a conductor such as 386 to terminal 387. All of the terminals 387 are connected to a common conductor which extends to the relay 392. The eighth register st, or the register set normally held in reserve, is connected in the following mannerrthe jumper, such as jumper 380, is cut and the terminal 379 is connected to terminal 383 and the terminal 381 is connected to the terminal 382. At armature 340 the conductor such as conductors 386 is moved from terminal 387 to terminal 388 which in turn is connected to an individual conductor 390 for controlling the relay 391.

It will now be assumed that the first seven 7 the register registers are busy and under such conditions ground at the various seven register sets have been disconnected from the common conductor 389,thereby permitting relay 392 to deenergize. Relay 392, upon deenergizing, removes ground from armature 396 thereby rendering the eighth register set selectable. At armature 397 and its resting contact, re-

- lay 392 prepares a circuit for relay 393. All

armature 398 and its resting contact, relay 392 connects ground to conductor 399 for energizing the all trunk busy relay ATB Fig. 2. Relay ATE, upon energizing, connects ground to the lower winding of all line relays such as 206 at the operator's position. The ground connections to the lower winding of the line relays extend over the con ductors 131 causing the energization of the relays 104 as previously explained. The latter relays, upon energizing, connect ground potentials to armatures 120 thereby rendering the outgoing trunks extending to the 0pcrators position busy.

it will now be assumed that a call has come n during the interval in which the last of he seven register sets was seized and the 'runks extending to the operators position were made busy. Under this condition such a call would operate the register selector such as C to cease the eighth register set. The call would then be completed in the same manner as previously described. However, as soon as the eigl'ith register set is seized, the circuit for relay 391 will be opened due to the reu'ioval of ground from conductor 390 whereupon said relay will deenergize and close a circuit for operating relay 393. At armature 394C relay 391 closes a shunt around the armature 396 so that if one of the iirst seven register sets becomes idle the operation of relay 392 will not interfere in any way with the call being set up on the eighth register set. When relay 393 is energized over the above traced circuit said relay removes ground from conductors 406 and the dead contacts in the terminal block on the I. D. F., Fig. l, thereby providing a plurality of stopping positions for the idle register selectors when all eight register sets are busy. [is soon as one register set becomes idle the circuit of relay 393 is broken and ground is again applied to the dead contacts.

Circuit arrangements have been made so that an operator can busy the incoming trunks at her position in groups of eight by means or" a plurality of keys such as key TK, 2. It being understood that the trunk lines terminating on a trunk key, such as 'lli, come from different autom atic exchanges or from different groups so that by the operation of only one or more keys all of the trunk lines from one particular oflice or group would not he made busy. By the aid of what is known as position linking keys an operator at a position may connect her headset to either position on either side of her. A position linking key for position 1 is shown in the dotted rectangle directly below POS. 1, below P08. 2 is shown the position linking key for position 2, or for the position with which the cord circuit O is associated, and in the dotted rectangle below PQS. 3 is shown a position linking key for position 3. By operating a certain plurality of keys T K at positions 1 and3 as well as position 2S0 that busy, the right half of position 3 is madev busy 1n a similar manner. The operator at position 2 will thenoperate the position linking keys at positions 1 and 2 thereby connecting her headset to the cord circuits at posishe may complete calls'coming into such positions during light traflic loads. j V f A description will now be given of the means by which the trunks extending from an automatic exchange to an operators position at the manual exchange aremade busy .whenthe'mam battery fuse atsuch position blows. In the upper lefthand corner of Fig.

2 there is .illustratedthe bus-bar to which the mainbattery is directly connected. 7 The conductor 273 illustrates the fuse wire by means of which the main battery is connected.

to the lower bus-bar and the conductor 27% illustrates the meansby which all of the apparatus at the operators position is connected to main battery, it being understood that allof the battery symbols shown at the Various relays and etc, are .diagrrmmatic, while in reality they all extend to the con- I ductoi-QFl. In case the fuse 273 should blow out forsomereason or other, the springconnected to the upper bus-bar wlllsprlng into contact with the alarm bus-bar 276 thereby connecting main battery to conductor 275 whichcloses energizing circuits to all the upper windings of the relays such as relay 200. The relays 200 are accordingly energized and at armatures 214i and 216 disconnect the conductors 130and; 131 from. the cord circuits and at armatures 216 and their working contacts connect ground to the trunk conductors 131 for energizing the refllays 104 in the repeaters E. The relays 104 energize and busies all repeaters E to so lectorswitches haying access thereto in the same manner as previously described.

At the extreme left of Fig. 2, there is shown .a test jack by means of which a test man may plug into cordcircuit O vfor testing purposes or for completing a call to a particular subscriber. When the test-man plugs intothe .test jack, the relay'QOO is energized over its lower winding and said relay busies therepeater E in the same manner as previously described. The testman maynow dial upthe register switches in th same manner as the calling subscriber. In Fig. 3. there is also shown a test ack by means of which a test man may routine the register 1 i set may be tested. It will be observed that with the aid of these test jacks the test man can plug into the cord circuit 0 or the register sets at the same time the operators calls at this position. c

Having described my 1nvent1on, what I in the appended claims:-

VJhat is claimed is:

equipment by means of which the reg- 70 position 15 muse without interfering with 1; In atele shone s stem trunk lines comi prising only two talking conductors extending from an automatic to a manual ex-l: change, a relay 111 each of said trunk lines at the automatic exchange for making 1ts,

associated trunk line busy when energized over a circuit including only one of the talking conductors of its associated trunk line, and means including. a second relay common to said. trunk lines at the manual exchange operable automatically to cause the energizetion of all said first relays of. the trunk lines o which are not inuse,

.2.-In a telephone system,--an*automatic exchange, a manual exchange, trunk lines comprising only two conductors extending from said automatic to said manual ex change, and means associated with; each' of said trunk lines at the automaticexchange and controlledover only one of its assoc1- at-ed conductors for making each of said trunk lines which are idle artificially busy and for making'each of the busy trunks artificially busy assoon as they become idle.

3. In a telephone system, an automatic exchange, a manual exchange, a two conductor trunk line extending from said automatic exchange to said manual exchange, a relay in said trunk line at said automatic exchange normally connected to one of the talking conductors of said trunk line, and means comprising a position lousying key'at the manual exchange for operating said relay overonly one of said talking conductors to busy said trunk line at the automatic ex-' change.

4. In a telephone system, an automatic exchange, a manual exchange, a two conductor trunk line extending fromwsaidautomatic exchangeto said manual exchange,

call register sets in said manual. exchange accessible to said trunk l1ne, a relay in said trunk line at said automatic exchange normally connected to one of thetalkingconductors of said trunk line, and means. oper- I ated when all said register sets become busy tor causing the encrglzat on of saidtrelay over only one of said talking'conductorsto busy said trunk l1ne at the change.-

5. In a telephone system, an automatic exchange, a manual exchange, a. two conductor trunk line extendingfromsaid automatic V automatic exexchange, a manual exchange,

exchange to said manualexchange, call register sets in said manual exchange accessible to said trunk line, a relay in said trunk line at said automatic exchange normally connected tonne of the talking conductors of said trunk line, a switch in said manual exchange for automatically preselecting idle register sets, and means operated when said switch is hunting for an idle register set for trunk line is connected to a source of current for operating purposes, and means operative responsive to the blowing of said fuse for causing the operation of said relay over one of said conductors to busy said trunk line at the automatic exchange.

7. In a telephone system, an automatic a two conductor trunk line extending from said automatic exchange to said manual exchange, call register sets in said manual exchange accessible to said trunk line, a relay in said trunk line at said automatic exchange normally connected to one of the talking conductors of sald trunk line, atest ack in "said manual exchange by means of which the trunk-line and said re 'ister sets in said manual exchange are tested, and means responsive to the seizure of said trunk line in the manual exchange by way of said test jack for causing the operation of said relay over one of said conductors to busy said trunk line at the automatic exchange.

8. In a call indicator system, a calling line, a. cord circuit accessible to said line, automatic register sets for registering called telephone numbers, a switch associated with said cord circuit, means for operating said switch to preselect an idle register set, means for extending a connection from said line to said cord circuit, a source of signalling current, and means responsive to the calling party dialling during the preselecting' operation of said switch for connecting said source to said line.

9. In a call indicator system, a calling line, a cord circuit accessible to said line, automaticregister sets for registering called telephone numbers, a switch associated with said cord circuit, means for operating said switch to preselect an idle register set, means for extending a connection from said line to said cord circuit, a source of signalling current, and means responsive to V the calling party dialling for connecting said source to said line in case said switch has preselected an open trunk.

10. In a call indicator system, a register set comprising a plurality of register switches, a restoring magnet for each of said switches, a circuit connnon to all of said magnets adapted when closed for energizin said magnets, a relay included in said circuit and adapted to be energized in series with any one or all of said magnets, and contacts on said relay for rendering said set artii'icially busy until all said switches have been returned to normal position.

11. In a call indicator system, a register sct comprising a plurality of register switches, a restoring magnet for each of said switches, a circuit common to all of said magnets adapted when closed for energizing said magnets, a relay included in said circuit and adapted to be energized in series with any one or all of said magnets, a holding conductor incoming to said set having a potential connected thereto when in use for rendering said set busy, a second relay in said set shunted by the potential on said holding conductor, said second relay operative when the potential is removed from the holding conductor for closing said common circuit, and contacts on said first relay for rendering said set artificially busy until all of said switches have been returned to normal position.

12. In a call indicator system, a manual exchange, trunk lines incoming from an automatic exchange and terminating in plug ended cord circuits in said manual c:-;change, means operative when a call is received for displaying the called number and for identi fying the cord circuit in use, and a key common to all said cord circuits momentarily operated by the operator in case the line is busy for causing the busy signal to be continuously transmitted from said cord circuit to the calling subscriber until the calling subscriber han up his receiver.

13. In a call indicator system, a manual exchange, trunk lines incoming from an automatic exchange and terminating in plug ended cord circuits in said manual exchange, means operative when a call is received for displaying the called number and for identi fying the cord circuit in use, a busy relay in each of said cord circuits adapted when encrgized to transmit a busy signal to the calling subscriber connected thereto, a'key common to all said cord circuits momentarily operated in case the called line is busy for causing only the busy relay in said cord circuit in use to be energized, and a locking circuit for maintaining said busy relay energized until the calling subscriber hangs up.

14:. In a telephone system, a manual exchange, an automatic exchange, a trunk line in said automatic exchange extending to and terminating in said manual exchange, call register sets comprising register switches in said manual exchange, a step by step switch 1n the manual exchange associated with said trim]; line for preselectmg an ldle register set. aswitchin rela in said, trunk line at the manual exchange operated responsive to the seizure of said trunk line at said auto matic exchangeror seizing said areselected register set, and means in said trunk line at he manual exchange for opening the circuit of said switchingrelaytoprevent its operation during the preselecting operation of said switch,

automatic step by step switch individual to each cord circuit for connecting its associated cord circuit with an idle register set when the cord circuit is taken into use, and a difierential relay in each cord circuit for controlling said switches to preselect idle register sets,

ahead ofcalls. c 7 I 16. In atelephone system, a manual exchange, a trunk line terminating in. a cord circuit in said exchange, automatic substations having access to said trunk line tor-calling subscribers in the manual exchange, a-

plurality of register sets for registering the telephone numbers of called manual stations,

; an automatic step by step switch for preselecting idle register sets ahead of calls, and attest relay in said cord circuit having a pair of contacts for controlling the operation of said preselecting switch and also controlling the operated conditional said relay when an idle register set is preselected.

17. In a call indicator system, a plurality of register sets normally accessible to calling automatic subscribers for registering the digits in a called telephone number, a reserve register'set artificially made busy and normally inaccessible to calling automatic subscribers, and means operative when all said plurality of register sets are in use for automatically rendering said reserve register set accessible to calling automatic subscribers.

18. In a telephone system,"a manual exchange, trunk lines terminating in, cord circuits at the manual exchange,automatio substations having accessto said trunk lines for calling subscribers in the manual exchange,

' a plurality of register sets normally accessible to calling automatic substations for registering the digits in a called telephone number, a

reserve register set artificially'made busy and normally lnaccessible to calling automatic substations,'means operated responsive to all said plurality of register sets being taken into use for rendering all of said trunk lines which are idleartlficially busy and for rendering sald reserve register set accessible to calling automatic substations automatic substations, and means "for selecting said reserve register set in case one of" said'trunklincs was seized beforesaid trunk mes were made busy.

19. In a telephone system, amanual ex-- change, trunk lines terminating in cord cir cuits at the manual exchange, automatic subscribers having access to said trunk lines for calling subscribers in the manual exchange, a plurality ofregister sets for registering the di its in a called telephone number,a reserve register set, a pluralityof switches each one I of which is individual to one of said cord'circuits 'tor preselecting idle register sets, said reserve setartificiallymade busy to said switches,means for taking into use said plurality of register :sets forv the purpose set forth, means operated responsive to all said plurality of register sets being taken into use tor-rendering all of saldtrunk llnes which, are'idle artificially busy and for rendering said reserve register set idle, and means for seizing said reserve register setin case oneof said trunk lines was seized during the interim in which the 'lastidl'e one of said plurality of registerv sets was taken into' ruse andthe trunk lines were artificially made busy.

20. In a telephone system, amanual -exchange, runk lines terminating incord oircuits at the manual exchange, ineanswhereby automatiosubscrlbers have access to said trunk lines tor calling subscribers in; the" manual exchange,a plurality of register sets for registeringl the digits in' a called telephone number, a reserve. registerset, a plurality of switches" each one of whlch 'is individual to; one of: said cord circuits tor preselecting' idle" register sets,

saidireserve register setartificially made busy to said switches, means tortaking into use said plurality otregister sets:for thepurpose set forth, means operated responsive to all said plurality of register sets :bei'ngtaken into use for renderingall'oi said trunk'lines which are idle artificially busy, and for ii'endering said reserve register set idle,'means for seizing said reserve register setjin'case one of said trunk lines was seized during the interim in which the last idle one of said pluralityof register-sets was taken into use and the trunk lines were artificially" made busy, a

dead banlrcontacts in banks of said switches artlficially made busy,'and means'operated responsive to the seizure of said'reserve register set for removing the artificially busy po tential from said dead bank contacts thereby establishing stoppingpositions for said preselecting switches. I 7' 21. In a telephone system, means for con necting a calling and a called line comprising a plug ending cord circuit, a ringingv circuit including a conductor of saidcord circuit, a ring-cut-oif circuit including a conductor of the called line and the said'conductor of said cord circuit, and meanseliective after the 

